• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    Enhancing performance of GaN-based LDs by using GaN/InGaN asymmetric lower waveguide layers

    2022-08-01 06:01:38WenJieWang王文杰MingLeLiao廖明樂JunYuan袁浚SiYuanLuo羅思源andFengHuang黃鋒
    Chinese Physics B 2022年7期

    Wen-Jie Wang(王文杰), Ming-Le Liao(廖明樂), Jun Yuan(袁浚),Si-Yuan Luo(羅思源), and Feng Huang(黃鋒)

    1Microsystem and Terahertz Research Center,China Academy of Engineering Physics,Chengdu 610200,China

    2Institute of Electronic Engineering,China Academy of Engineering Physics,Mianyang 621999,China

    Keywords: asymmetric waveguide structure,InGaN multiple quantum wells,optical absorption loss,optical

    1. Introduction

    Nitride materials are ideal materials for semiconductor lasers in the ultraviolettovisible spectrum range. With the advantages of small size, high efficiency, long life, and fast response speed, GaN-based semiconductor laser is widely used in laser display, laser lighting, underwater communication, biomedicine, and other civil and military fields.[1–8]In particular, the GaN-based violet laser diodes (LDs) have attracted attention as a new laser source for high-density optical disk storage.[9,10]To realize such applications,high power GaN LD is significantly important. However, the electrooptical power conversion efficiency of commercial GaN-based laser diodes is still less than 40%. The structural design and material growth of GaN-based violet LDs have been studied extensively in the past. But achieving ultra-high performance of GaN-based violet LDs is still a big challenge. There remain some problems to be solved further in the realization of high power GaN LD, such as high total optical loss and optical field leakage. Many methods have been proposed to suppress the total optical loss and improve the optical field distribution for GaN-based violet LDs,such as complex upper waveguide,[11–13]undoped thickoptical-waveguide (TOW) layer,[14,15]and the nanoporous GaN cladding layers.[16]These complex structures with undoped InGaN wave guides are difficult to realize the high quality epitaxy on a quantum well structure, especially near a p-AlGaN electron barrier layer with high doping concentration.

    At the same time,by increasing the thickness and refractive index of upper waveguide layer, the optical field distribution gradually moves into the N-type region,so that optical absorption loss is reduced and optical field distribution in Pregion is improved, which brings higher output power. However, when the optical field center is in quantum well region,how to further adjust optical field distribution and reduce optical absorption loss to improve the output power is not covered in the existing literature. Comparing with the traditional LD structure proposed by Nakamuraet al.,[17,18]the optical characteristics,especially optical field distribution,can be improved by using an asymmetric quantum wells with a thick last quantum barrier.[19]To solve this problem,an asymmetric InGaN quantum well LD with the optical field center in the quantum well region, is selected as a research object in this work. The influence of GaN/InGaN lower waveguide layer on the photoelectric performance of GaN-based violet LDs is investigated numerically by using the PIC3D software.The influence of InGaN-IL parameters on the optical absorption loss and optical field distribution are clarified by designing a composite GaN/InGaN lower waveguide layer,so as to explore the ways to further improve the output power of asymmetric quantum wells LDs.

    2. Device structure and simulation setup

    The schematic diagram of asymmetric quantum well violet GaN-based LD with composite GaN/InGaN asymmetric lower waveguide structure is shown in Fig. 1, where the thickness and doping concentration of each layer are indicated. The violet GaN-based LD consists of a 1-μm thick Si-doped n-type GaN layer, a 1-μm thick Si-doped ntype Al0.08Ga0.92N cladding layer (n-CL), a composite lower waveguide layer(LWG)which is comprised of a 100-nm thick Si-doped n-type GaN layer and an InGaN-IL,a multiple quantum well (MQW) active area, a 20-nm thick Mg-doped ptype Al0.2Ga0.8N electron blocking layer (EBL), a 100-nm thick GaN upper waveguide layer (UWG), a 500-nm thick p-type Al0.07Ga0.93N cladding layer (p-CL), an 80-nm thick Mg-doped p-type GaN layer, and a 20-nm thick Mg-doped p++-type GaN contact layer. The active region consists of three period unintentionally-doped In0.15Ga0.85N/InGaN multiple quantum wells(MQWs).The InGaN barrier layer has the indium content changing from 4%to 1%in the upward direction of the substrate. Compared with the conventional threeperiod 3-nm thick InGaN/15-nm thick GaN quantum wells,the asymmetric quantum well can effectively improve the laser performance,especially increase the thickness of the last barrier layer.[19]In order to keep the thickness of the asymmetric quantum well consistent with the thickness of the conventional three-period-thick MQWs, the thickness of the well layer of the asymmetric quantum well is 3 nm,the same as that of the conventional quantum well, and the thickness of the last barrier layer is increased to make the center of optical field located in the MQW region and improve the optical field distribution. The thickness for each of the first three barrier layers is set to be 5 nm, and the thickness of the last barrier layer is set to be 45 nm, so that the optical field can be concentrated in the quantum well region. The cladding layer thickness n-CL is set to be 1 μm in order to better confine the light within the quantum well and waveguide layer. Thicker n-AlGaN layer is unnecessary and will increase the absorption loss.The optical and electrical performance of GaN-based LDs with GaN/InxGa1-xN asymmetric lower waveguide layers of different thicknesses or indium contents are investigated respectively. The thickness values of n-InGaN insertion layers are different, ranging from 0 nm to 600 nm, with the indium content being 0.02. On the other hand, the indium content of n-InGaN insertion layer varies from 0 to 0.07,with the thickness being 300 nm.

    In this work, the optical and electrical characteristics of these LD structures are theoretically simulated by the Crosslight Device Simulation Software (PIC3D, Crosslight Software Inc.). The PIC3D is designed to simulate the operation of GaN-based laser diode in three-dimensional space by self-consistently solving Poisson’s equation and current continuity equation through using the finite element method. In such a calculation, both the p-type electrode and n-type electrode are set to be of ideal Ohmic contact. The cavity lengths and ridge widths of these GaN-based lasers are all 800 μm and 2 μm,respectively. The P-electrode covers the ridge area and the N-electrode covers the entire underside.The screening factor is set to be 0.25,[20]and the band offset(ΔEc/ΔEg)is set to be 0.67.[21]Meanwhile,for the n-type layer and the p-type layer, their absorption coefficients are set to be 5 cm-1and 50 cm-1,[22]respectively, except for the heavily Mg-doped GaN contact layer, whose absorption coefficient is taken as 100 cm1. The reflectivity values of both front cavity surface and rear cavity surface are both set to be 0.19. Moreover,the refractive index values of AlxGa1-xN and InxGa1-xN are calculated from the refractive index formulas.[23–26]For the violet LDs with a lasing wavelength of around 416 nm, the refractive index values of InN, GaN and AlN are set to be 3.4167,2.5067, and 2.0767, respectively. The refractive index values of InxGa1-xN and AlxGa1-xN are calculated using an approximate method as follows:

    Fig. 1. Schematic diagram of device for asymmetric quantum well GaNbased violet LD with composite GaN/InGaN asymmetric lower waveguide structure.

    3. Results and discussion

    3.1. Effect of thickness of InGaN insertion layer

    At first,the influence of InGaN-IL on the emission properties of violet LDs is investigated by simulation when the thickness value varies from 0 nm to 600 nm, with the indium content maintained at 2%. The curves of output power and voltageversusinjection current for various values of In0.02Ga0.98N insertion layer thickness are shown in Fig. 2.According to the output power–current curve, the slope efficiency of layer is calculated and its variation with thickness is shown in the insert of Fig.2(b),indicating that the slope efficiency is much higher than that in Refs. [11,12], and slightly lower than that in Ref.[13]. The dependence of threshold current and output power(under an injection current of 160 mA)on InGaN insertion thickness as shown in Fig.3.

    Fig.2. Curves of(a)output power versus injection current when thickness of In0.02Ga0.98N insertion layer varies from 0 nm to 600 nm,and(b)curves of voltage versus injection current for violet LDs,with inserts showing slope efficiencies.

    Fig. 3. The output power and threshold current versus thickness of In0.02Ga0.98N-IL for violet LDs.

    It is found that the threshold current remains first at 38.2 mA when the thickness of InGaN-IL rises from 0 nm to 100 nm, and then markedly increases to 74.4 mA with the further increase of InGaN-IL thickness. Meanwhile, the output power reaches a maximum value of 176.13 mW when the InGaN-LWG thickness increases to 300 nm, which is 24%higher than that of the basic structure with 142 mW, and then decreases sharply when the thickness increases to over 300 nm. It demonstrates that for violet LDs, the composite GaN/In0.02Ga0.98N waveguide with In0.02Ga0.98N insertion thickness less than 600 nm has better performance than GaN waveguide,and the optimal thickness is 300 nm. In addition,the current–voltage curve is basically unchanged, indicating that the increase of InGaN-IL thickness does not significantly increase the resistance.

    In fact, the threshold current and the output power are mainly influenced by the optical confinement properties and optical field distribution.[27]Therefore, the influence of InGaN-IL thickness on the optical performance of GaN-based violet LDs will be discussed in detail below.

    Fig.4. Curves of(a)optical confinement factor and total optical loss and(b)center of optical field offset and FWHM versus thickness of In0.02Ga0.98NIL for violet LDs,with insert showing optical field distribution and dashed lines denoting InGaN-IL position.

    The data of optical properties reflecting optical field distribution are shown in Fig. 4, where the thickness of InGaNIL rises from 0 nm to 600 nm. In Fig. 4(a), the optical confinement factor (OCF) increases slightly from 2.4% to 2.56% when the thickness of InGaN-IL increases from 0 nm to 70 nm. Meanwhile, the total optical loss (TOL) decreases from 8.73 cm-1to 6.46 cm-1with the thickness of InGaNIL increasing. It indicates that the increasing of InGaN-IL thickness can reduce optical loss and a little enhance the confinement factor,thereby will better restricting the optical field.Therefore,the performance of violet LDs can be improved due to the decrease of TOL and increase of OCF.Simultaneously,it can be seen that with the increase of the IL layer thickness in Fig.4(a),the optical field concentrates more inside the InGaN-IL layer. However,the optical field peak deviates from the quantum wells. Even if more optical fields are distributed inside the InGaN-IL layer, the optical absorption loss further decreases, but the OCF may be reduced by shifting the peak position of the optical field.This is consistent with the trend of OCF in Fig.4(a)as the thickness of the barrier layer changes.Therefore,with the increase of the IL layer thickness,the peak position of the optical field moves from the MQW region to the n-type region,and the optical confinement factor slowly grows to a maximum value and then decreases rapidly. Meanwhile,the mode gain is the product of OCF and material gain. When the thickness exceeds 100 nm,the peak gain decreases gradually,confirming that the optical field gradually enters into the InGaN-IL layer,which is not conducive to OCF.The decrease of mode gain leads the threshold current to increase,which is consistent with the change trend of OCF in Fig.4(a).

    Furthermore,the more details of optical field distribution are shown in Fig.4(b). The center of optical field(COF)offset is used to describe the position of the optical field center relative to the quantum well region. The value represents the depth from the peak position of the optical field to the InGaNIL.Most of optical field moves far away from p-type area with the thickness of InGaN-IL increasing,thus reducing TOL due to the smaller absorption coefficient in n-type area. In addition, the center of optical field (COF) offset shifts slowly from quantum well region to the InGaN-IL and full width at half maximum (FWHM) of the optical field decreases from 0.32 μm to 0.29 μm when the thickness rises from 0 nm to 100 nm. It demonstrates that the optical field is better compressed and thus optical field is confined more near the MQWs region. As the InGaN-IL is inserted, the difference in refractive index between InGaN-IL and AlGaN cladding increases,and the optical field is far from the P-type region and better compressed into the InGaN-IL close to the quantum well region,thus reducing the TOL and slightly increasing the OCF.However, when the InGaN-IL thickness exceeds 100 nm, the optical field center gradually deepens into the InGaN waveguide layer. At the same time,the FWHM gradually increases,and the OCF decreases due to serious downward leakage of the optical field. The reduction of TOL can offset the adverse effects caused by the optical field leakage, so that the output power reaches a maximum value when the thickness of the InGaN-IL is 300 nm.Moreover,after the insertion layer thickness reaches to over 300 nm,a small reduction in TOL is still not enough to slow down the output power decline caused by optical field leakage. On the other hand,the band structure of LD is basically unchanged when the insertion layer thickness increase to 300 nm, and the percentage of electron leakage current(PELC)decrease within 1%,indicating that the InGaN insertion layer thickness has little influence on the electrical performance of this LD,which is consistent with the current–voltage curve in Fig.2(b).

    3.2. Effect of indium content of InGaN insertion layer

    As mentioned above, the LD with an optical light field center in the quantum well region can increase the output power by 24% by inserting a 300-nm thick InGaN-IL. However,it has not been determined whether the output power can be further improved. Therefore, based on the 300-nm thick insertion layer,we further explore the power improvement potential by changing the indium content of the InGaN-IL.

    Figure 5 shows that when the indium content in InGaNIL increases from 0 to 0.07, the threshold current increases from 40.1 mA to 55.2 mA.Meanwhile,when the indium content of InGaN-IL increases from 0 to 0.04, the output optical power first increases from 169 mW to 178.5 mW, which is 25.7%in enhancement with respect to the reference structure of asymmetric GaN waveguide LD.Compared with the effect of InGaN-IL thickness, the effect of indium content change on LD output power and threshold current are relatively small.When the indium content increases from 2%to 4%,the output power only increases by 2 mW and the increment ratio is less than 1.2%.

    Fig.5.Output power and threshold current versus indium content of InGaNIL for violet LD.

    Figure 6(a)shows that most of optical field leaks into the InGaN-IL when the indium content increases from 0 to 0.07.However, vast majority of optical field is concentrated in the GaN/InGaN LWG when the indium content is more than or equal to 0.04. Figure 6(b)shows that the center of optical field decreases abrupt from 2.35 μm to 2.26 μm with the indium content increasing and then reaches a constant at 2.26 mm when the indium content is more than 0.04. In addition, figure 6(b)also shows that the FWHM of optical field decreases from 0.41 μm to 0.28 μm when the indium content increases from 0 to 0.07,indicating that most of optical field moves far from MQW region and concentrates when the indium content is more than 0.04. It demonstrates that optical field leakage is enhanced due to the decrease of optical confinement caused by a large refractive index of GaN/InGaN LWG,thus threshold current increases obviously.

    Fig. 6. (a) Optical field distributions for various indium contents, and (b)center of optical field and FWHM versus indium content of InGaN-IL for violet LD,with red dotted line denoting interface between InGaN-IL layer and the MQW.

    Meanwhile,the trend of TOL and OCF changing with indium content in Fig. 7 also confirm the above statement and discussion. The TOL decreases rapidly, and moderates when the indium content is greater than or equal to 0.04. The reason is that as the center of the optical field gradually deepens into the InGaN-IL and is fixed at 2.26 μm,the proportion of the optical field with a low optical absorption coefficient in the composite waveguide layer and the quantum well region gradually increases,especially in the InGaN-IL.With the gradual increase of indium content,the rapid decrease of TOL can compensate for the adverse effects caused by the decrease of OCF,so that the LD output power reaches a maximum value when the indium content of InGaN-IL is 0.04. Similarly, the electrical properties of LD based on the GaN/InGaN composite lower waveguide layer structure show that the variation of indium content has a weak influence on the fluctuation of electron current leakage,and the fluctuation range is within 1.5%.

    Fig.7. Optical confinement factor and total optical loss versus indium content of InGaN-IL for violet LD.

    Fig.8. (a)Electron concentrations and(b)hole concentrations varying with position at 160 mA forward current for three samples.

    In addition,the influence of the thickness and the indium composition of InGaN-IL on the electron and hole concentration are analyzed,and the results are given in Fig.8,showing that the electron and hole concentration in the quantum well increase slightly with the change of the thickness and composition, while In4-300 increases more. However, the variation of InGaN-IL thickness does not significantly change the energy band,especially the electron barrier layer interface. The band diagram shows that the thickness and the indium composition of InGaN-IL have slight effects on the effective potential barrier height of electrons and holes. ΔEcand ΔEvare around 192.3 meV and 193.7 meV, respectively, which is also confirmed in the PLEC diagram. When the indium component of InGaN-IL is high,a potential well will be formed between the GaN low waveguide layer and the first quantum barrier layer as indicated in Fig.9. In this case,the carriers may converge and recombine in the potential well.As mentioned in Ref.[28],the calculation results of recombination rate show that the carrier in InGaN-IL increases with indium content increasing. Since this part of the carrier does not contribute to oscillation,it results in low injection ratio and waste of carriers. Therefore,when the indium content of InGaN-IL layer is greater than 4%,the decrease of current injection ratio is also the cause of LD deterioration. It is suggested that using GaN/InGaN instead of GaN as LWG can improve the performance of LD,but the indium content should be kept at a relatively low level.Therefore,when a 300-nm thick In0.04Ga0.96N insertion layer is used, the laser output power is improved by 25.7% compared with the LD reference structure of the symmetric GaN waveguide layer.

    Fig.9. (a)Energy band diagram of conduction band and(b)valence band,with InGaN-IL thickness being 300 nm and injection current being 160 mA.

    4. Conclusions

    In this work,the approach to improving the output power of violet GaN-based LD with the optical field centered in the quantum well region is proved by using asymmetric GaN/InGaN composite lower waveguide layer. Compared with the indium content of InGaN-IL,the thickness of InGaNIL is a decisive factor for improving the laser performance.The maximum output power of the laser reaches 178.5 mW,when the thickness of InGaN-IL is 300 nm and the indium content is 0.04. Further theoretical analysis indicates that the thickness and indium content of InGaN-IL are both beneficial to pushing the optical field towards the InGaN lower waveguide layer and greatly reducing the total optical loss, which makes up for the negative effect of the reduction of optical confinement factor, thereby improving the performances of GaN-based violet LDs.

    Acknowledgements

    Project supported by the National Natural Science Foundation of China (Grant Nos. 62004180 and 61805218), the Science Challenge Project, China (Grant No. TZ2016003-2-1), and the National Key Research and Development Program of China (Grant Nos. 2017YFB0403100 and 2017YFB0403103).

    亚洲av在线观看美女高潮| 一级片免费观看大全| 日日啪夜夜爽| 人妻系列 视频| 色婷婷久久久亚洲欧美| 亚洲成人手机| 高清av免费在线| 精品一区二区三卡| 三级国产精品片| videossex国产| www.熟女人妻精品国产 | 国产国拍精品亚洲av在线观看| 91国产中文字幕| 九草在线视频观看| 韩国高清视频一区二区三区| 丰满迷人的少妇在线观看| 国产麻豆69| 中文字幕人妻丝袜制服| 亚洲精品美女久久久久99蜜臀 | 日日啪夜夜爽| 久久人人97超碰香蕉20202| 啦啦啦啦在线视频资源| 少妇熟女欧美另类| 国产在视频线精品| 9色porny在线观看| av免费在线看不卡| 日本色播在线视频| 婷婷色麻豆天堂久久| 天堂中文最新版在线下载| 亚洲人成77777在线视频| 看免费成人av毛片| 国产又色又爽无遮挡免| 亚洲第一av免费看| 精品人妻一区二区三区麻豆| 亚洲精品中文字幕在线视频| 一二三四在线观看免费中文在 | 亚洲精品456在线播放app| 欧美日韩av久久| 大片免费播放器 马上看| 日本猛色少妇xxxxx猛交久久| 99香蕉大伊视频| 中文天堂在线官网| 插逼视频在线观看| 99国产精品免费福利视频| 日韩精品免费视频一区二区三区 | 80岁老熟妇乱子伦牲交| 国产乱人偷精品视频| 蜜桃国产av成人99| 国产无遮挡羞羞视频在线观看| 亚洲av免费高清在线观看| 久久99热这里只频精品6学生| 又粗又硬又长又爽又黄的视频| 两性夫妻黄色片 | 看非洲黑人一级黄片| 欧美精品一区二区大全| 人体艺术视频欧美日本| 欧美激情极品国产一区二区三区 | 制服诱惑二区| 亚洲成国产人片在线观看| 日韩一本色道免费dvd| 中文天堂在线官网| 天天操日日干夜夜撸| 亚洲av欧美aⅴ国产| 国产成人精品无人区| 你懂的网址亚洲精品在线观看| 精品福利永久在线观看| 国产在线视频一区二区| 欧美激情 高清一区二区三区| 日韩欧美一区视频在线观看| 亚洲国产看品久久| 亚洲国产毛片av蜜桃av| 亚洲国产欧美日韩在线播放| 国产精品久久久久久精品古装| 人妻系列 视频| 激情视频va一区二区三区| 一二三四在线观看免费中文在 | 如何舔出高潮| 青春草国产在线视频| 2021少妇久久久久久久久久久| 一二三四中文在线观看免费高清| 人人妻人人添人人爽欧美一区卜| 有码 亚洲区| 国产片内射在线| 国产高清国产精品国产三级| 久久久久人妻精品一区果冻| 黑人欧美特级aaaaaa片| 国产综合精华液| 亚洲 欧美一区二区三区| 国产免费一级a男人的天堂| 女人久久www免费人成看片| 午夜福利,免费看| 99re6热这里在线精品视频| 热99久久久久精品小说推荐| 亚洲欧美成人精品一区二区| 久久亚洲国产成人精品v| 免费观看在线日韩| 亚洲国产精品999| 十八禁网站网址无遮挡| 国产在线免费精品| 成人免费观看视频高清| 97超碰精品成人国产| 高清视频免费观看一区二区| 深夜精品福利| 久久久久精品人妻al黑| 国产在线免费精品| 看十八女毛片水多多多| 人体艺术视频欧美日本| 夫妻性生交免费视频一级片| 免费高清在线观看日韩| 香蕉丝袜av| 99视频精品全部免费 在线| 欧美日韩综合久久久久久| 免费观看在线日韩| 亚洲激情五月婷婷啪啪| 亚洲一区二区三区欧美精品| 街头女战士在线观看网站| 五月伊人婷婷丁香| 色婷婷av一区二区三区视频| 精品一区二区三区四区五区乱码 | 亚洲一码二码三码区别大吗| 你懂的网址亚洲精品在线观看| 国产精品一区二区在线观看99| 亚洲成人av在线免费| 99国产综合亚洲精品| 中文字幕另类日韩欧美亚洲嫩草| 久久99一区二区三区| 成人亚洲精品一区在线观看| 曰老女人黄片| 精品亚洲乱码少妇综合久久| 一区二区av电影网| 成人手机av| 成人综合一区亚洲| 黄网站色视频无遮挡免费观看| 中文字幕免费在线视频6| 国产色爽女视频免费观看| 久久这里有精品视频免费| 日韩在线高清观看一区二区三区| 精品少妇黑人巨大在线播放| 成人免费观看视频高清| 中文字幕另类日韩欧美亚洲嫩草| 亚洲精品视频女| 波多野结衣一区麻豆| 搡女人真爽免费视频火全软件| 一本色道久久久久久精品综合| 丰满乱子伦码专区| 久久国产亚洲av麻豆专区| 午夜老司机福利剧场| 国产片特级美女逼逼视频| 亚洲成人一二三区av| 免费黄频网站在线观看国产| 精品视频人人做人人爽| 尾随美女入室| 岛国毛片在线播放| 精品国产一区二区三区久久久樱花| 交换朋友夫妻互换小说| 亚洲精品久久久久久婷婷小说| 超色免费av| 精品久久久久久电影网| 国产激情久久老熟女| 色吧在线观看| 亚洲成国产人片在线观看| 成人影院久久| 精品少妇久久久久久888优播| 毛片一级片免费看久久久久| 毛片一级片免费看久久久久| 女性被躁到高潮视频| 亚洲五月色婷婷综合| 高清毛片免费看| 日本欧美视频一区| 日韩精品免费视频一区二区三区 | 免费女性裸体啪啪无遮挡网站| a级毛片在线看网站| 免费在线观看黄色视频的| 国产激情久久老熟女| 嫩草影院入口| 美女国产高潮福利片在线看| 天堂俺去俺来也www色官网| 久久人人97超碰香蕉20202| 欧美97在线视频| 99re6热这里在线精品视频| 精品国产一区二区三区久久久樱花| 18在线观看网站| 一区二区av电影网| 一级爰片在线观看| 高清视频免费观看一区二区| 日韩一本色道免费dvd| 日韩三级伦理在线观看| 久久韩国三级中文字幕| 99热这里只有是精品在线观看| 精品一品国产午夜福利视频| 大陆偷拍与自拍| 免费观看a级毛片全部| 青春草亚洲视频在线观看| 亚洲欧美一区二区三区国产| 日韩视频在线欧美| 九九在线视频观看精品| 少妇被粗大猛烈的视频| 亚洲精品av麻豆狂野| 热re99久久精品国产66热6| 宅男免费午夜| 最新的欧美精品一区二区| 亚洲情色 制服丝袜| 成年av动漫网址| 高清黄色对白视频在线免费看| av天堂久久9| 男人舔女人的私密视频| 国产女主播在线喷水免费视频网站| 黄片播放在线免费| 日本91视频免费播放| 亚洲精品视频女| 99久久综合免费| 在线观看免费视频网站a站| av播播在线观看一区| 国语对白做爰xxxⅹ性视频网站| 少妇被粗大的猛进出69影院 | 欧美xxxx性猛交bbbb| 国产成人精品福利久久| 青春草亚洲视频在线观看| 久久精品国产鲁丝片午夜精品| 久久久亚洲精品成人影院| 日日摸夜夜添夜夜爱| 国产免费又黄又爽又色| 26uuu在线亚洲综合色| 久久久久网色| 亚洲国产日韩一区二区| 国产高清国产精品国产三级| 国产免费又黄又爽又色| 国产精品秋霞免费鲁丝片| 欧美精品亚洲一区二区| 香蕉丝袜av| 亚洲国产精品一区三区| 精品亚洲成国产av| 国产极品粉嫩免费观看在线| 欧美成人午夜精品| av.在线天堂| 天美传媒精品一区二区| 国产又色又爽无遮挡免| 在线观看三级黄色| 久久精品国产a三级三级三级| 久久久久久久久久久久大奶| 99九九在线精品视频| kizo精华| 精品久久国产蜜桃| 丝袜喷水一区| 国产精品无大码| 国产精品久久久久成人av| 久久av网站| 国产精品国产三级国产av玫瑰| 性色av一级| 日本黄大片高清| 国产成人免费无遮挡视频| 80岁老熟妇乱子伦牲交| 菩萨蛮人人尽说江南好唐韦庄| 亚洲欧美日韩另类电影网站| 国产精品久久久久久久电影| 美女福利国产在线| 午夜福利,免费看| 五月玫瑰六月丁香| 高清毛片免费看| 这个男人来自地球电影免费观看 | 视频中文字幕在线观看| 一区二区日韩欧美中文字幕 | 超碰97精品在线观看| 日本黄大片高清| 高清不卡的av网站| 国产精品不卡视频一区二区| 欧美精品国产亚洲| 一个人免费看片子| 精品久久久久久电影网| 中文字幕亚洲精品专区| 1024视频免费在线观看| 成年人午夜在线观看视频| 久久久国产精品麻豆| 亚洲精品国产色婷婷电影| 国产日韩欧美亚洲二区| av福利片在线| 亚洲成人一二三区av| 母亲3免费完整高清在线观看 | 丝袜脚勾引网站| 免费av不卡在线播放| 黑人欧美特级aaaaaa片| 国产精品国产av在线观看| 菩萨蛮人人尽说江南好唐韦庄| 99热这里只有是精品在线观看| 国产免费福利视频在线观看| 高清不卡的av网站| 亚洲在久久综合| 国产男女内射视频| 精品亚洲成a人片在线观看| 黄片无遮挡物在线观看| av女优亚洲男人天堂| 国产精品一区二区在线观看99| 在线观看美女被高潮喷水网站| 日韩欧美一区视频在线观看| 国产成人免费观看mmmm| 乱人伦中国视频| 中文欧美无线码| 欧美人与性动交α欧美软件 | 亚洲成人手机| 赤兔流量卡办理| 最近最新中文字幕免费大全7| 成人二区视频| 街头女战士在线观看网站| 欧美日韩av久久| 久久人妻熟女aⅴ| 中文字幕av电影在线播放| 亚洲精品一二三| 国产一区亚洲一区在线观看| 天天躁夜夜躁狠狠躁躁| av免费观看日本| 99热全是精品| 亚洲av中文av极速乱| 咕卡用的链子| 五月开心婷婷网| 成人漫画全彩无遮挡| 日韩精品免费视频一区二区三区 | 18禁动态无遮挡网站| 欧美日韩成人在线一区二区| 99热6这里只有精品| 国产女主播在线喷水免费视频网站| 国语对白做爰xxxⅹ性视频网站| 黄色配什么色好看| 最近中文字幕高清免费大全6| 蜜桃在线观看..| 中文精品一卡2卡3卡4更新| 高清毛片免费看| 两性夫妻黄色片 | 免费女性裸体啪啪无遮挡网站| 男男h啪啪无遮挡| 亚洲精品美女久久久久99蜜臀 | 人人妻人人澡人人爽人人夜夜| 国产成人av激情在线播放| 两个人免费观看高清视频| 在线观看三级黄色| 国产又爽黄色视频| 久久人人爽人人爽人人片va| 国产日韩欧美在线精品| 五月玫瑰六月丁香| 在线精品无人区一区二区三| 国产精品三级大全| 80岁老熟妇乱子伦牲交| 国产精品欧美亚洲77777| 少妇精品久久久久久久| 十分钟在线观看高清视频www| 中文字幕免费在线视频6| 亚洲天堂av无毛| 久久久精品区二区三区| 纵有疾风起免费观看全集完整版| 精品一区二区三区视频在线| 大话2 男鬼变身卡| 我要看黄色一级片免费的| 亚洲成人av在线免费| 卡戴珊不雅视频在线播放| 免费看光身美女| 视频中文字幕在线观看| 国产探花极品一区二区| 亚洲,一卡二卡三卡| 亚洲,欧美精品.| 大码成人一级视频| 精品一区二区三卡| 最近最新中文字幕免费大全7| 亚洲精品一区蜜桃| av片东京热男人的天堂| 老女人水多毛片| 99热网站在线观看| 日本91视频免费播放| 女人精品久久久久毛片| 一个人免费看片子| 精品午夜福利在线看| 国产亚洲av片在线观看秒播厂| 视频区图区小说| 香蕉精品网在线| 午夜av观看不卡| 美女视频免费永久观看网站| 久久精品久久久久久噜噜老黄| 欧美日韩亚洲高清精品| 亚洲欧洲国产日韩| 老熟女久久久| 七月丁香在线播放| 亚洲第一av免费看| 亚洲欧洲日产国产| 国产成人午夜福利电影在线观看| 欧美精品av麻豆av| 欧美老熟妇乱子伦牲交| 黑人欧美特级aaaaaa片| 亚洲精品美女久久av网站| 天堂8中文在线网| 尾随美女入室| 国产综合精华液| 精品少妇黑人巨大在线播放| 国产成人免费无遮挡视频| 伦理电影大哥的女人| 国产1区2区3区精品| 久久鲁丝午夜福利片| 国产av国产精品国产| 国产一区二区三区综合在线观看 | 成人亚洲欧美一区二区av| av卡一久久| 久久国产精品大桥未久av| 亚洲国产最新在线播放| 一级毛片黄色毛片免费观看视频| 成年人午夜在线观看视频| 交换朋友夫妻互换小说| 一边摸一边做爽爽视频免费| 国产黄频视频在线观看| 女人被躁到高潮嗷嗷叫费观| 少妇人妻 视频| 久久精品国产a三级三级三级| www.色视频.com| 日本91视频免费播放| 日韩三级伦理在线观看| 两个人免费观看高清视频| 国产亚洲最大av| 熟女av电影| 成人漫画全彩无遮挡| 久久精品国产亚洲av涩爱| 高清不卡的av网站| 欧美最新免费一区二区三区| 国内精品宾馆在线| 一级,二级,三级黄色视频| 三级国产精品片| 大香蕉久久成人网| 纯流量卡能插随身wifi吗| 免费播放大片免费观看视频在线观看| 亚洲国产精品国产精品| 在线观看三级黄色| 亚洲欧美成人精品一区二区| av在线播放精品| 女性生殖器流出的白浆| 最后的刺客免费高清国语| 亚洲欧美一区二区三区黑人 | 18+在线观看网站| 黄片播放在线免费| 成人免费观看视频高清| 大香蕉97超碰在线| 亚洲精品视频女| 免费看av在线观看网站| 精品国产一区二区久久| 欧美97在线视频| av一本久久久久| 高清视频免费观看一区二区| 毛片一级片免费看久久久久| 国产免费福利视频在线观看| 少妇熟女欧美另类| 五月伊人婷婷丁香| 精品亚洲成国产av| 精品久久国产蜜桃| 亚洲成av片中文字幕在线观看 | 国产精品久久久久久精品电影小说| 亚洲精品乱码久久久久久按摩| 麻豆精品久久久久久蜜桃| 国产精品无大码| 日韩制服丝袜自拍偷拍| 中文精品一卡2卡3卡4更新| 久久毛片免费看一区二区三区| 天堂8中文在线网| 女性生殖器流出的白浆| 欧美 亚洲 国产 日韩一| 男的添女的下面高潮视频| 日韩一区二区三区影片| 哪个播放器可以免费观看大片| 久久人人97超碰香蕉20202| 99久久中文字幕三级久久日本| 日韩视频在线欧美| 国产日韩一区二区三区精品不卡| 国产一区二区三区综合在线观看 | 久久久久久久久久久久大奶| 亚洲精品456在线播放app| www.色视频.com| 精品视频人人做人人爽| 校园人妻丝袜中文字幕| 最黄视频免费看| 国产亚洲精品久久久com| 久久久亚洲精品成人影院| 成人二区视频| 国产精品国产三级国产av玫瑰| 国产av一区二区精品久久| 黄片播放在线免费| 人体艺术视频欧美日本| 亚洲五月色婷婷综合| 日韩伦理黄色片| 国产精品麻豆人妻色哟哟久久| 男女边吃奶边做爰视频| 九草在线视频观看| 老司机亚洲免费影院| 国产精品偷伦视频观看了| 日韩制服丝袜自拍偷拍| 啦啦啦在线观看免费高清www| 亚洲国产精品999| 亚洲国产av影院在线观看| 精品少妇久久久久久888优播| 亚洲欧美成人精品一区二区| 久久久久久久久久成人| 高清不卡的av网站| 成人毛片60女人毛片免费| 另类精品久久| 日日撸夜夜添| 日本91视频免费播放| 中文字幕最新亚洲高清| videosex国产| 久久国产亚洲av麻豆专区| 满18在线观看网站| 成人二区视频| 又大又黄又爽视频免费| 秋霞伦理黄片| 啦啦啦中文免费视频观看日本| 国产一区二区激情短视频 | a 毛片基地| 亚洲天堂av无毛| 高清欧美精品videossex| 国产极品天堂在线| 国产 精品1| 蜜臀久久99精品久久宅男| 日韩制服丝袜自拍偷拍| 99久久中文字幕三级久久日本| 18+在线观看网站| freevideosex欧美| 久久久久久久国产电影| 亚洲综合色网址| 国产探花极品一区二区| 美女内射精品一级片tv| 男的添女的下面高潮视频| 欧美 日韩 精品 国产| 欧美精品一区二区免费开放| 在线观看人妻少妇| 久久综合国产亚洲精品| 精品人妻熟女毛片av久久网站| 人妻人人澡人人爽人人| 亚洲av日韩在线播放| 一边摸一边做爽爽视频免费| 99热网站在线观看| 国产色婷婷99| 亚洲欧美日韩卡通动漫| 久久久久久久久久久久大奶| 超碰97精品在线观看| 69精品国产乱码久久久| 丝瓜视频免费看黄片| 亚洲国产av新网站| 亚洲精华国产精华液的使用体验| 丰满少妇做爰视频| 九九在线视频观看精品| 国产69精品久久久久777片| 亚洲美女视频黄频| 少妇精品久久久久久久| 久久久久久久精品精品| 亚洲一码二码三码区别大吗| 韩国av在线不卡| 亚洲综合色惰| 亚洲性久久影院| 中文字幕av电影在线播放| 久久久久久久久久久久大奶| 丝瓜视频免费看黄片| 777米奇影视久久| 在线天堂中文资源库| 在线 av 中文字幕| 汤姆久久久久久久影院中文字幕| 国产亚洲av片在线观看秒播厂| 9色porny在线观看| 久久鲁丝午夜福利片| 丝袜脚勾引网站| 一区二区av电影网| 乱码一卡2卡4卡精品| 在线观看美女被高潮喷水网站| videosex国产| 国产日韩欧美视频二区| 日本与韩国留学比较| 国产成人精品一,二区| 国产成人精品婷婷| 蜜桃在线观看..| 国产精品女同一区二区软件| 寂寞人妻少妇视频99o| 日韩 亚洲 欧美在线| 少妇人妻久久综合中文| 一级爰片在线观看| 日日摸夜夜添夜夜爱| 午夜福利,免费看| www日本在线高清视频| 免费观看av网站的网址| 国产黄色视频一区二区在线观看| 日本免费在线观看一区| 欧美日韩亚洲高清精品| 美女国产视频在线观看| 亚洲,欧美精品.| 午夜福利视频精品| 婷婷色麻豆天堂久久| av黄色大香蕉| 搡老乐熟女国产| 成年美女黄网站色视频大全免费| 亚洲精品第二区| 少妇的丰满在线观看| 久久这里有精品视频免费| av国产久精品久网站免费入址| 成人手机av| 97在线人人人人妻| 午夜免费鲁丝| 夫妻性生交免费视频一级片| 热re99久久精品国产66热6| 日韩精品有码人妻一区| 国产精品不卡视频一区二区| 欧美国产精品va在线观看不卡| 欧美亚洲 丝袜 人妻 在线| 国产一区有黄有色的免费视频| 国产高清国产精品国产三级| 制服丝袜香蕉在线| 天堂俺去俺来也www色官网| 久久人人爽人人爽人人片va| 人人妻人人爽人人添夜夜欢视频| 精品一区二区三区视频在线| 国产精品无大码| 亚洲少妇的诱惑av| 精品一区在线观看国产| 久久久国产精品麻豆| 国产亚洲精品久久久com| 成人国产麻豆网| 在线观看一区二区三区激情|